1. Field of the Invention
The invention relates to a means of reshaping light beams transmitted from the fluted lens cover of a sealed beam lamp to permit the lamp to conform to certain photometric specifications pertaining to automobile lamps. More particularly, the invention relates to a method of shaping lamp beams to certain specifications by progressively covering the individual flutes molded within the lens cover to determine the location of the respective flutes or portions of individual flutes which are contributing unwanted light.
2. Description of the Prior Art
The Society for Automotive Engineers (hereinafter referred to as SAE) over 40 years ago promulgated a series of recommended practices for automobile headlamps and other lights associated with the automobile, related to the safety aspects of lights. The objective was to set a series of photometric, mechanical and durability tests, and procedures for those tests, which have been adapted by the original equipment Automotive manufacturers. Recently, the states and Federal Government became safety conscious and have adopted the recommended practices of the SAE and enacted laws to govern the specifications of automobile lights.
The fifty states and Canadian provinces have formed an association called American Association of Motor Vehicle Administrators (hereinafter called AAMVA). The AAMVA acts as a central clearing house for all member states so manufacturers only need to gain certified approval from AAMVA to be legal in the states and provinces.
The California Highway Patrol (hereinafter called CHP) was the first state to become a stringent enforcer of the SAE regulations along with additional standards they set as regulations that were adopted into law. The final outcome was a general set of rules and regulations adopted by the various agencies that have set standard specifications adopted by all states to legally regulate the design and manufacture of specific automobile lights.
It is not necessary that lights for automobiles be of a sealed beam lamp type to be accepted as long as they meet photometric standards. However, it has been proven that sealed beam lamps are more practical to manufacture and maintain.
Standards set forth for specific types of sealed beam lamps are in most cases easily met, but in the case of auxiliary low beam and passing lamps, the specifications are so rigid that manufacturers have been unable to design a sealed beam fluted lens cover for a lamp that will consistantly meet the photometric specifications.
In a strict geometric-optical sense the sealed beam lamp cover represents more than just a simple lens, which is defined as an optical system bounded by two refracting surfaces having a common axis. The sealed beam lamp lens cover is composed of a number of different optical light control elements, such as prisms or cylindrical lenses positioned in either vertical or horizontal planes and molded into the glass cover. These light control elements are commonly called flutes.
As is known to those skilled in the art, all of the attempts by varying flute patterns and flute shapes in the sealed beam lamp lens cover have thus far proven futile in perfecting a lamp which meets the auxiliary low beam automobile head lamps SAE J582a specifications. The auxiliary low beam specification (SAE J582a) is referred to herein by way of example only. Various types of fluted lens cover specifications for other automobile headlamps could be met by utilizing the method as set out herein.
The procedures and information for the photometry of automobile headlamps is set out in a book titled "Light and Color of Small Lamps", by Boris Merik and published by General Electric Company. Specific information relating to photometry can be found on pages 17, 18, 19, 124, 125, 126, 127, and 217.